Sawicki Music Supply is a mail-order business that accepts merchandise orders by telephone and mail.

All payments must be prepaid with a major credit card. Once an order is received, the item is either found in inventory and shipped immediately, the item is not found in inventory and is ordered from the manufacturer, or a notice is sent to the customer indicating the item is no longer stocked.

Required:
Prepare a context-, intermediate-, and elementary level dataflow diagram for Sawicki Music Supply.
For the elementary-level diagram, explode the inventory function.